1. Field of the Invention
The invention relates to a device for liquid separation and filtration of compressed gases, especially compressed air, nitrogen, rare gases, natural gases or the like, filtration being used for drying and cleaning of the compressed gas. In particular one such device is of great importance in the production of compressed breathing air.
2. Description of Related Art
There is already a device for liquid separation and filtration for drying and cleaning of compressed gases which has a tank which is closed on the bottom and top, within which, concentrically to one another, there are a liquid separation means and a filter means which is designed preferably in the form of a filter cartridge. In the outer concentric annular space, there is a liquid separation means which works according to the centrifugal principle and which comprises a separation space and a condensate collection space, and which is physically, but not fluidically, separated by means of a separating wall relative to the concentrically inside filter means in the form of a filter cartridge. In this device, the compressed gas first enters the centrifugal liquid separation means in which liquid is separated, for example, in droplet form, from the gas flow and then is captured in the condensate collection space. The exit side of the liquid separation means is connected by flow communications to the downstream filter means for drying and cleaning, the separating wall between the concentrically outside liquid separation means and the concentrically inside filter means causing flow deflection.
If, in this known device, the separating wall between the concentrically arranged liquid separation means and the filter means begins to leak, the liquid separated by the liquid separation means can travel into the downstream filter means; this adversely affects the operating reliability of such a device. Furthermore, the known device has a relatively large diameter since the inside filter means is located concentrically outward of the liquid separation means with the interposition of a separating wall so that such a device takes up a relatively large amount of installation space.
The primary object of the present invention is, therefore, to provide a device for liquid separation and filtration for drying and cleaning of compressed gases which, while surmounting the above described difficulties, has a structure that is as compact as possible, which works reliably and especially also accomplishes an improved degree of liquid separation.
According to the invention, a device for liquid separation and filtration for drying and cleaning of compressed gases, especially compressed air, with a tank closed on the top and bottom, is provided, within which a centrifugal liquid separation means with a separation space and a condensate collection space, and a filter means, preferably in the form of a filter cartridge, are located with communicating flow such that the compressed gas is fed into the tank through the liquid separation means, then through the filter means, and the compressed gas which has been cleaned and dried in this way, passes to the outlet of the tank which is characterized in that the tank is made in the form of a continuous hollow cylinder, the liquid separation means being axially upstream of the filter means in the form of a filter cartridge in a common tank, and the filter cartridge being positioned leaving a small annular gap to the inside wall of the common tank which is in communications with the outlet side of the liquid separation means.
In the design of the device in accordance with the invention, the diameter of the device can thus be greatly reduced so that the device takes up reduced installation space and even with constricted space conditions can be accommodated without difficulties.
In the design of the device in accordance with the invention this is achieved especially by the liquid separation means with the separation space and the condensate collection space being located in the common tank horizontally in a separate area axially in terms of flow in front of the filter means. In this way, a separate separating wall between the liquid separation means and the filter means can be omitted since the filter means, which is preferably designed in the form of a filter cartridge, especially with its bottom, directly forms the spatial separation relative to the axially upstream liquid separation means. Therefore, in the device in accordance with the invention the operating reliability can also be increased since the danger of leak formation in a separating wall is eliminated.
Since, due to the axially successive arrangement of the liquid separation means and the filter means, the compressed gas leaving the liquid separation means must also traverse a further path along the filter means as far as the inlet into it, this area can be used as a fine separation means since the compressed gas which is flowing in a spiral on this route to the entry into the filter means strikes the cooler tank wall, and in this way, further fine separation or post-separation can take place up to the inlet into the filter means. As a result, therefore, the degree of liquid separation can be further increased.
Furthermore, the filter cartridge of the filter means is located in the tank interior, leaving a small annular gap to the inside wall of the housing, the annular gap being in communication with the outlet side of the liquid separation means. In this small and narrow annular gap, the compressed gas leaving the liquid separation means is accelerated. The narrowness of the gap increases the turbulence of the flow. This improves condensate separation on the filter cartridge wall and on the cooler inside wall of the tank so that, on this path to the inlet into the filter means, further post-separation or fine separation of liquid can take place. Therefore, the device in accordance with the invention has an extremely favorable degree of liquid separation.
Preferably, the device in accordance with the invention is designed such that the compressed gas, in the area of the bottom of the tank, enters the separation space of the liquid separation means, and the condensate collection space is formed in interaction with the bottom of the tank. Therefore, only the bottom area of the tank need be made accordingly, such that, at the lowest possible point, there is the condensate collection space in which the liquid portion which has been separated by means of the liquid separation means is collected. This yields a device which is designed to be as compact as possible and easy to produce, especially also in the centrifugal liquid separation area.
Expediently, the device in accordance with the invention is designed such that the bottom of the filter cartridge, which is located axially downstream, directly borders the separation space of the liquid separation means. Therefore, for spacial and physical separation of the separation space and the filter means, separate additional means are not necessary, but the bottom of the filter cartridge is used itself as one of the boundary walls of the separation space of the liquid separation means. This greatly simplifies the structure of the device in accordance with the invention, especially in terms of construction and production engineering.
Alternatively, underneath the filter cartridge, in the common tank, there can be a separating wall which can be provided in addition for delineating the separation space.
According to one preferred embodiment in accordance with the invention, the design is such that the compressed gas enters via an inlet tube which projects into the separation space of the liquid separation means which is located axially underneath the filter cartridge, and has at least one exit opening in the vicinity of its upper end. In the approach in accordance with the invention, an axially relatively short inlet tube for the compressed gas is thus sufficient, and the separation space is formed and bounded directly by the bottom part of the housing and by the inside wall of the housing. In this design, especially the condensate collection space is formed by the lower area of the separation space which also has an axial distance relative to the bottom of the filter cartridge from the outlet in the bottom area of the filter cartridge so that the result with reliable operation is that the condensate in the condensate collection space cannot travel back again into the gas flow which has passed through the filter cartridge of the filter means, and which then emerges on the bottom side of the tank. In this way, remixing with the cleaned and dried compressed gas flow can be effectively avoided.
In summary, it is important in the invention that the liquid separation means and the filter means for drying and clearing the compressed gases be spatially located axially in succession and that the filter means is located axially over the centrifugal liquid separation means without any additional separating walls, especially a narrow annular gap being formed between the outside wall of the filter cartridge of the filter means and the inside wall of the housing which enables post-separation or fine separation of the liquid.
The invention is explained in detail below with reference to one preferred embodiment and the attached drawings.